Thursday, September 29, 2016

Broken metal plane repair

Yesterday we were in port, and most surprisingly it didn't rain. We are in Bergen, and on an average it rains here 400 days per year (or there about)..

After realising that it was 22 years ago I had last done any brazing/welding of cast iron, I decided to read up a bit on the subject. Basically the advice was to:
1) Use a flame with oxygen surplus.
2) Preheat the parts to 350 - 400 dgC.
And off course the usual stuff about chamfering and how to hold the flame (15-30 degree angle).

I mounted two pieces of angle bar in a vise on the deck. One would hopefully keep the sole falt, and the other should keep the plane aligned sideways.

A fairly important trick for cast iron is to first use a flame (oxygen surplus) directly on the crack, to burn away any carbon deposits.

After this I did my best to preheat evenly to 400 dgC. I then started brazing with a special filler material intended for cast iron. The biggest challenge was that I couldn't flip the plane on the side to do the major parts of the crack, and this particular type of filler works best if applied on a horizontal piece.
I did the best I could, and at a point I decided that I couldn't do much more.

The next suggestion from the welding handbook was to let the item cool slowly packed in dry sand or in some insulation material. I elegantly skipped that part and just reduced the intensity of the flame and heated a bit on the plane now and then till I reached 150 dgC.
After that I just let it cool down.

Once cold I rinsed it off in water and took it to the workshop.

The sole had a cup in the middle, so I flattened it using a file and later some emery paper. It still has a small area behind the mouth where it is possible to slip a piece of paper under. But I think it might be OK despite that. If not I'll just flatten it some more later.
Sideways it was also a bit off, but it was mostly on the forward most part of the plane. I flattened until I could see that the nicker was in line with the aft part of the plane, and then I stopped. I have never used the plane with the blade in the forward position, and I doubt I ever will, so no need to fuss to much over it.

The conclusions to the project:
By using the cast iron filler instead of the bronze filler, the repair job is a little bit more hidden, and a bit stronger.
The structured original paint of the plane is destroyed. And the entire plane needs to be washed again because it makes your hands dirty when you try to hold it.
It is possible to repair a broken cast iron plane. BUT it is better if you don't drop it in the first place!

Plane positioned on angle bars. 

Chamfered crack.

Burning away the carbon deposits.

How I checked the temperature (this is cooling down).

First shot of the repair job.

Flattening the sole, pen marks show my progress.
I did flatten it more, but didn't take more pictures.

Light colour shows where it is flat.

Repair job on the inside.


  1. Wow! You might actually be able to use this again. I'm impressed. It turned out way better than I expected. I suppose I shouldn't be surprised.

    1. Right now the biggest problem is that it gets your hands dirty, but I think that is fixable.
      Also the blade needs to be touched up, but I'll do that at home.
      Now there's a school box that needs to be completed :-)
      I'll race you to it!

  2. Congrats on the successful repair!

  3. Now that shows what can be done with some knowledge and the willingness to use it! Great stuff. Let us know how it cuts after the blade is fixed.


    1. Hi Matt.

      It might take a while before I get around to sharpening the blade. I have to race to complete my school box before Brian Eve does.
      But I think (hope) that it will still be OK.
      I'll see if I remember to blog about it once I sharpen the blade. If not I'll probably rememebr it next time I have to use the plane out here.

      I would have liked to take some more pictures of the actual process, but since I operated an oxygen/acetylene torch with one hand and the filler material with the other hand, I didn't have any left for taking pictures :-)


  4. Great job, metal work is a complete mystery to me I have hard enough time grappling with wood

    you did well not getting wet with 400 days of rain a year LoL

    1. Hi Peter.

      Metal work is not so hard when you have learned how to do it. But I guess most things are like that.

      I don't know how they manage to get that many days put into one year here in Bergen :-) But it really does rain a lot..


  5. This is great to know, every other reference I've come across says that broken plane bodies are scrap metal. Thanks for setting this right.

    1. Hi Jefski

      Don Weber has got an old plane that has been repaired a bit like this. Except his is repaired using a bronze filler. I think his repair job looks better, but after all he is a blacksmith by trade as well, so I can live with that.

      But that plane is the only one I have seen that has been in use after being repaired.
      The biggest problem is to get everything straight after putting it back together. But I like the general idea of repairing it.
      the value will most likely sink to nothing for a collector, but I like the honesty of a good repair job.

      Here's a close up of his plane.
      I can't see if it was broken in both sides or just on one side. One side would make repairing it a lot easier because there wouldn't be any problems in lining up the parts, and you could flip the plane to the side for a good brazing position.


    2. It seems like a good idea to avoid buying anything with a broken body, but I'll look for a good welder if I break one of my favorites. What part of Denmark are you in? :) Thanks again, and for the Don Weber image.

    3. Hi Jefski
      I think in total the welding/brazing part took about half an hour, that includes finding angle bar and setting it all up etc. A good welder in a shore based shop ought to be able to do a job somewhere along those lines, depending off course on the severity of the crack.
      A shore based welder will also have the benefit of a non moving shop floor, and the possibility to work under a roof without setting off a fire alarm :-)

      I live in the north western part of Denmark, on an island called Mors.